, Volume 33, Issue 10-11, pp 2139-2144
Date: 02 Oct 2012

Photopyroelectric Microscopy of Porous Ceramics

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Abstract

Porous ceramics has capital importance in a wide variety of applications as in the case of gas and humidity sensors; in these applications an important fact is that the ceramic structure must insure intercommunication between one side and the other. Several techniques has been used in order to have information about the ceramic structure; among these, photopyroelectric (PPE) spectroscopy is an option to be used in porous ceramic structure characterization. In PPE microscopy, an image of the sample thermal response can be obtained by 2D scanning of a focused beam across a surface, which yields localized information on the possible presence of subsurface features which is an important property of porous ceramics. Recently porous ceramics based on barium titanate mixed with silicon dioxide have been developed to be used as gas and humidity sensors. By the use of PPE microscopy, porous ceramics were analyzed with two different resolutions as a result of the variation of the light modulation frequency. The light modulation frequency is related not only to scanning depth, but also to thermal scale length which gives us the minimum sample length that can be studied and is also related with its thermal diffusion length.